ES2885524T3 - Procedure for mitigating uplink-downlink interference in a heterogeneous network - Google Patents

Abstract

A method for a communications network including a first cell and a second cell, the method comprising: receiving, by a base station in the first cell, an authority indicator from a base station in the second cell regarding a determination of whether the first cell should autonomously select a time division duplex uplink-downlink configuration; determining (410), by the base station of the first cell, based on the authority indicator, whether the first cell should autonomously select the time division duplex uplink-downlink configuration; applying (420), by the base station of the first cell, the autonomously selected time division duplex uplink-downlink configuration, when the first cell should autonomously select the time division duplex uplink-downlink configuration; and providing (430), by the base station of the first cell, traffic loading information to the base station of the second cell when the first cell should not autonomously select the time division duplex uplink-downlink configuration.

Description

DESCRIPTION

Procedure for uplink-downlink interference mitigation in a heterogeneous network

Background:

Country:

Communication systems such as the Third Generation Partnership Project (3GPP) Long-Term Evolution (LTE) Advanced (LTE-A) can benefit from various enhancements. These enhancements may include enhancements to LTE time division duplex (TDD) for traffic adaptation and uplink (UL) - downlink (DL) interference management.

Description of related art:

LTE TDD currently enables asymmetric UL-DL mappings by providing seven semi-statically configured UL-DL TDD configurations shown in Figure 1. These mappings can provide between 40% and 90% DL subframes. The current mechanism to adapt the UL-Dl allocation based on the system information change procedure with a period of 640 ms. The specific configuration of TDD UL/DL is reported semi-statically by signaling System Information Block, Signaling, Type 1 (SIB-1).

As shown in Figure 1, the various UL-DL assignments can have a switching point periodicity of 5 ms or 10 ms. In addition, the assignments may include assignments for downlink, D, uplink U, and special S. The special subframes may be, for example, a protection period. If UL/DL TDD dynamic reconfiguration is directly adopted in LTE systems including both homogeneous networks and heterogeneous networks, it may cause UL-DL interference in conflicting subframes, due to independent and different TDD UL/DL configurations in neighboring cells, such as eNode B (eNB)-to-eNB interference and user equipment (UE)-to-UE interference. This type of UL-DL interference can affect UL Signal to Interference Plus Noise (SINR) when eNBs are located in line of sight (LOS) or located close to each other or in DL SINR when UEs are located on the edge of a cell.

Considering the impact of UL-DL interference, UL/DL TDD dynamic reconfiguration is mainly adopted in small cells, for example, pico cells, femto cells and LTE-Hi cells. As shown in Figure 2, two small cells, cell 1 and cell 2, in the coverage of a macro cell can use a ^{dynamic reconfiguration function t} D ^d UL DL according to the variation of uplink-downlink traffic of each cell, while the macro cell uses a fixed UL/DL TDD setting to avoid UL-DL interference in the wide area network.

In this case, the UE1 in DL served by a base station (BS) of cell 1 may receive interference from UE2 in the neighboring cell due to the uplink transmission of UE2. In the same way, the UE2 in UL served by a BS of cell 2 may receive interference from the BS of cell 1, due to the downlink transmission of cell 1. In particular, when UEI is close to UE2 , the interference may be higher between the two UEs. Similarly, when the two cells are located in LOS or close to each other, the BS-to-BS interference can be higher between two BSs.

Currently, in the actual deployment, all neighboring cells use the same UL/DL TDD configuration and thus avoid the UL-DL interference explained above. Dynamically changing TDD UL/DL settings bring new intercell interference scenarios like eNB to eNB and UE to UE. Therefore, there is no specific conventional interference mitigation scheme with respect to this UL-DL interference.

US2010/220597A1 describes techniques for facilitating synchronization establishment and/or mitigating interference with a TDD access point base station in a wireless communication environment.

MEW POSTCOM: "Necessity and feasibility of using different uplink-downlink configurations for TDD HeNB in heterogeneous networks" (R1-103688) discusses the need and feasibility of applying different uplink-downlink configurations between TDD HeNB in heterogeneous networks.

WO2013/100581A1 describes techniques for changing the TDD uplink and downlink configuration.

Summary

The invention relates to non-transient methods, base stations and computer readable media as set forth in the claims.

Brief description of the drawings:

For a proper understanding of the invention, reference should be made to the accompanying drawings, in which: Figure 1 illustrates seven current types of UL/DL TDD configurations.

Figure 2 illustrates the dynamic reconfiguration of TDD UL/DL in a heterogeneous network.

Figure 3 illustrates a procedure according to certain embodiments.

Figure 4 illustrates another procedure according to certain embodiments.

Figure 5 illustrates a further method according to certain embodiments not covered by the claims.

Figure 6 illustrates a system according to certain embodiments.

Detailed description:

Certain embodiments provide time division duplex (TDD) uplink (UL)/downlink (DL) dynamic reconfiguration. More specifically, certain embodiments realize the flexibility of having dynamic TDD UL/DL configuration in a TDD system to match uplink and downlink traffic variation. Furthermore, certain embodiments avoid having a negative impact of UL-DL interference.

For example, certain embodiments may avoid or reduce UL and DL interference when two small cells, such as a picocell or femtocell, in the coverage of a macrocell use a flexible UL/DL TDD reconfiguration. In certain embodiments, for example, a base station or eNode B (eNB) of a macrocell may send an authority indicator to a picocell. The picocell can send traffic load information to the cell eNB. The traffic load information may include the instantaneous traffic ratio between the DL and UL, or the amount of data available waiting for scheduling in the DL and UL, or the traffic ratio during the predefined statistical time scale. The eNB macro can select a TDD UL/DL configuration for the picocell with a relatively small number of conflicting subframes, based on interference information, such as path loss, as well as traffic loading information.

Thus, for example, an eNB macro can determine who has the authority to control the peak's DL/UL TDD settings based on interference conditions between two peaks. The macro may determine that one or both peaks may have autonomous control, or the macro may determine that the macro has control.

For example, if the interference is low, such as when the two peaks are located very far apart, then the macro can send an authority indicator to the peak and the peak can determine its own TDD DL/UL settings. On the other hand, if the interference is high, such as when two peaks are located close to each other, then the macro can determine an appropriate TDD DL/UL setting for the peak and send it to the peak.

The eNB spike can send traffic information to, which can serve as the basis for the macro's decision on authority. For example, pico can send an instantaneous traffic ratio between DL and UL, pico can send an indication of an amount of data available while waiting for scheduling on DL and UL, or pico can send a traffic ratio during a layover. of predefined statistical time.

The eNB macro can select a TDD UL/DL setting for the picocell with the fewest conflicting subframes based on an interference table, a reported downlink-to-uplink ratio, or an amount of traffic waiting from the scheduling. the eNB peak. For example, the macro selection routine can be configured to minimize the number of conflicting subframes.

Thus, certain embodiments provide a semi-autonomous TDD configuration management method, in which the macro eNB (MeNB) can determine if an intercell interference between two PeNBs exceeds a threshold for at least one of the PeNBs and can control at least one of the PeNBs. one of the PeNB's TDD configurations when the threshold is exceeded, while allowing autonomous TDD configuration by each of the PeNBs when the threshold is not exceeded.

Thus, certain embodiments provide a dynamic TDD UL/DL configuration scheme controlled by the eNB macro for small cells associated with the eNB macro. The scheme mainly focuses on u L-DL interference coordination in heterogeneous network scenarios where macro and small cells operate on different carriers.

For example, the eNB macro knows the location of each associated picocell, eg those picocells within or near the cell coverage area. The eNB macro can also know the path loss between neighboring picocells. This path loss information may be calculated by, collected directly by small cells that, with additional DL receiving capabilities, obtained by a practical field test after deployment, or obtained in some other way. The macro eNB can compare the anticipated interference with a threshold to decide if two pico eNBs deployed in neighboring cells cause severe interference with each other. In addition, the eNB macro may maintain tables that record the picocells that may have severe interference to or from each specific picocell. The threshold used by the eNB macro can be adjusted to keep the UL-DL interference within a predetermined range of a target level.

The eNB macro can look up the interference table and send the authority indication to each eNB peak, using, for example, X2 or S1 interface signaling. The eNB macro can transfer the authority to determine the TDD UL/DL setting to the picocell that satisfies the condition that no other picocell is registered in the interfered table of this picocell. Otherwise, the authority can remain in the macro eNB.

If a pico eNB has the authority to determine the TDD UL/DL setting, then the pico eNB can autonomously change its TDD UL/DL setting according to its own instantaneous traffic ratio between DL and UL or the amount of data available waiting for the schedule in DL and UL or the traffic ratio during the predefined statistical time scale.

If a pico eNB does not have the authority to determine its own TDD UL/DL settings, the pico eNB can send the instantaneous traffic ratio between DL and UL, the amount of data available waiting for scheduling in DL and UL, or the traffic ratio during the predefined statistical time scale to the eNB macro. This information may be sent via return signaling, such as X2 or S1 interface signalling. The information can be sent periodically or with activation.

In the case where the eNB macro is authoritative, the eNB macro may select the TDD UL/DL setting for the picocell by looking up an interference table and considering the TDD UL/DL setting on the interfered picocell.

For example, the eNB macro may select a TDD UL/DL configuration with the fewest, or at least the most, conflicting subframes. Table 1, discussed below, provides an example. The eNB macro may consider the reported downlink to uplink ratio or the amount of traffic waiting for scheduling at the eNB peak.

After the TDD UL/DL setting for a particular peak is determined, the eNB macro can send the setting to the peak, for example, via X2 or S1. The pico can then change its TDD UL/DL setting in compliance with the decision of the eNB macro.

Alternatively, a pico eNB without the authority to determine the TDD UL/DL configuration can also send the expected TDD ^u L/DL configuration according to the traffic ratio statistic between DL and UL to the macro eNB through interface X2 or S1. Then, the eNB macro can select the TDD UL/DL setting for picocell with a small number of conflicting subframes according to Table 1, discussed below, and can take into account the TDD UL/DL setting expected by this. peak.

An alternative approach for macro-spiking operated on the same carrier may be as follows. The eNB macro can send its own TDD UL/DL configuration to each eNB peak within its coverage via, for example, X2 or another interface. Then, each peak eNB can implement Table 1, described below, in its own memory and can estimate the path loss to the macro eNB by listening to a reference signal from the macro eNB. If the path loss is greater than a threshold plus a margin, which can be called a delta, the pico eNB can select the TDD UL/DL configuration according to its own traffic variation in UL and DL.

Otherwise, the eNB peak may select the TDD UL/DL configuration with a relatively small number of subframes in conflict with the TDD UL/DL configuration of a macrocell according to Table 1, described below.

Therefore, the dynamic TDD reconfiguration feature can be adopted and avoid severe UL-DL interference. The interference coordination approach described above can also be applied to Femtocells or LTE-Hi cells.

As mentioned above, in a heterogeneous network, a macro cell may use a fixed UL/DL TDD configuration. However, TDD UL/DL dynamic reconfiguration can be used in small cells, such as pico cells, femto cells, or LTE-Hi cells. At the beginning of each TDD pattern switching period, the pico eNB, Femto base station, or LTE-Hi AP can select a TDD UL/DL pattern with the most suitable DL-UL subframe ratio. A basis for selection may be the relative amount of total traffic on the downlink and uplink waiting for programming at the base station. In this way, D ^l throughput gain or UL throughput gain or DL throughput and UL throughput gain due to traffic adaptation can be obtained.

When the macrocell and the smaller cells operate on different carriers, there is no co-channel interference between the macrocell and the smaller cells. This scenario can be addressed by certain embodiments.

After the deployment of each small cell, the macro eNB may need to know the location of each associated peak within its coverage and the path loss between neighboring picocells. This path loss information can be calculated by the macro or collected directly by the small cells with additional DL receive capabilities. Other ways to obtain path loss information can also be used, including a practical field test after deployment.

The eNB macro can then compare the path loss information with a threshold, to decide whether any two peak eNBs deployed in neighboring cells cause severe interference with each other. If the path loss between two picocells is less than the threshold, then the eNB macro can maintain a table to record the two picocells. Otherwise, the eNB macro may skip registering the two picocells as an interference pair. Alternatively, the eNB macro maintains an interference table to record the level of mutual interference between any two picocells, including both low interference and severe interference, where the difference between low and severe is determined by comparing path loss with threshold. This threshold can be adjusted to keep the UL-DL interference at a target level, within a margin.

In use, the eNB macro can look up the interference table and send an authority indication to each eNB peak, for example when using an X2 or S1 interface signaling. For example, a bit can be used as an indication of authority. In one approach, a bit with a value of 1 represents that pico has the authority to determine its own TDD UL/DL configuration, while a bit with a value of 0 represents that pico has no such authority and needs to report its traffic variation or relationship of traffic in DL and UL to macro and comply with the decision of the macro. For a picocell that satisfies the condition that no other picocell is registered in the interfered table of this picocell, the eNB macro can transfer the authority to determine the TDD UL/DL setting to the picocell by setting the authority indication to "1 ". Otherwise, the eNB macro can maintain this authority in the eNB macro by setting the authority flag to "0".

The pico eNB that has the authority to determine the TDD UL/DL setting can autonomously change its TDD UL/DL setting according to its own instantaneous traffic ratio between DL and UL or the amount of data available waiting for scheduling in DL and UL or the ratio of traffic during the predefined statistical time scale.

An eNB spike without the authority to determine the UL/DL TDD setting may, periodically or upon activation, send the instantaneous traffic ratio between DL and UL, the amount of data available waiting for scheduling in DL and UL, or the ratio of traffic during the predefined statistical time scale to the eNB macro via return signaling, for example via X2 or S1 interface signaling.

The eNB macro can select the TDD UL/DL setting for this picocell by looking up the interference peak table and considering the TDD UL/DL setting on the interfered peak. The macro can select the TDD UL/DL configuration with the fewest conflicting subframes with the interfered picocell according to Table 1, also taking into account a reported ratio between downlink and uplink traffic expected by the scheduling in the table. picocell.

Table 1 below illustrates a series of conflicting subframes between any two different TDD configurations within a radio frame. A special subframe can be viewed as a conflicting subframe with a DL subframe due to UpPTS in the special subframe when calculating the number of conflicting subframes between a UL/DL TDD configuration with a 5 ms switch point and another with a switch point of 10 ms.

Table 1

For example, if the path loss between peak 1 and peak 2 is less than the threshold, then it can be assumed that they suffer from severe mutual interference. Thus, pico 1 can use the TDD UL/DL 2 configuration to provide a heavy DL resource for DL transmission. Peak 2 may also want to use some heavy DL configurations to accommodate downlink burst data transmission. Thus, if pico 2 has the authority to independently select its own TDD UL/DL configuration, it can select TDD UL/DL configuration 3 or 4, which is also a TDD UL/DL heavy DL configuration and can provide resources from the 70% or 80% for the downlink. Looking up Table 1, the number of conflicting subframes is 4 or 3 between the TDD UL/DL setting 2 and 3 or 4, respectively. So 40% or 30% of peak 1 and peak 2 resources may experience UL-DL interference.

Instead, when using a UL-DL interference coordination scheme, since the path loss between peak 1 and peak 2 is less than the threshold, then they are recorded on the eNB macro side. Therefore, both peaks may not have the authority to determine their own TDD UL/DL settings autonomously and may need to wait for the decision of the macro. Therefore, the eNB macro can select the ^t D ^d UL/DL configuration for peak 2 with fewer conflicting subframes with picocell 1, according to Table 1. The eNB macro can take into account the reported relationship between the downlink and uplink traffic on peak 2. The eNB macro can select TDD UL/DL configuration 2, instead of configuration 3 or 4, for peak 2. Thus, there is no UL-DL interference between peak 1 and peak 2 due to the same TDD UL/DL setting. Consequently, system performance can benefit from dynamic TDD reconfiguration without UL-DL interference.

Alternatively, a pico eNB without the authority to determine the TDD UL/DL setting may also send its expected TDD ^u L/DL setting to the eNB macro via the X2 interface; then the eNB macro selects the TDD UL/DL setting for the picocell with least conflicting subframes according to Table 1 and takes into account the TDD UL/DL setting expected for this peak.

For example, by assuming that the path loss between peak 1 and peak 2 is less than a threshold, then the macro can determine that they suffer from severe mutual interference. In a particular example, peak 1 uses the UL/DL TDD setting 5 to provide the heaviest DL resource for the DL stream. Peak 2 may want to use some heavy UL configurations to accommodate uplink burst data transmission. If the pico 2 has the authority to independently select its own TDD UL/DL configuration, it can select the TDD UL/DL 0 configuration, which is ^{UL's heaviest T d} D UL/DL configuration and can provide 60% of the uplink resources. Looking up Table 1, the number of conflicting subframes is 6 between the UL/DL TDD setting 5 and 0. Thus 60% of the resources may experience UL-DL interference.

Instead, when using UL-DL interference coordination, since the path loss between peak 1 and peak 2 is less than the threshold, then they are recorded on the eNB macro side. Therefore, the eNB macro can select the TDD UL/DL setting for peak 2 with the fewest conflicting subframes with picocell 1, according to Table 1, and can take into account the expected TDD UL/DL 2 setting of the cell. For example, the eNB macro may select the TDD UL/DL 1 setting for peak 2 which may provide 40% of the resources for the uplink and the number of conflicting subframes may be 4. Although the TDD setting UL/D ^l 1 provides less uplink resources than UL/DL 0 TDD configuration, there is less UL-DL interference between peak 1 and peak 2. Thus system performance can still benefit from TDD reconfiguration dynamic with less interference UL-DL.

In addition, based on the intercell interference status of the network, the eNB macro can also return the TDD UL/DL settings of all affected cells to the default TDD UL/DL settings or the balanced TDD UL/DL configuration, such as configuration 1. Thus, the eNB macro selection may provide less gain than the dynamic TDD UL/DL configuration, but the overall network performance can still be improved.

In another example, peak 1 may be close to peak 2. However, peak 1 may be dominated by heavy UL traffic, while peak 2 may be dominated by heavy DL traffic. Thus it can be difficult to find a suitable TDD UL/DL setting for Peak 1 to avoid interference with Peak 2. Another way to manage the system is to adjust the TDD UL/DL setting for Peak 1 as well as pico 2, or towards the TDD UL/DL balanced configuration, for example, configuration 1. In this way, both picocells can have less interference and network performance can be improved.

Once the TDD UL/DL setting for the picocell is determined, the eNB macro can send it to the pico eNB via X2 or S1. The pico can then change its TDD UL/DL setting, by complying with the decision of the eNB macro.

If the macro and pico operate on the same carrier, co-channel interference may occur. Therefore, each associated picocell within the coverage of the macro may receive co-channel interference with the macro.

In this case, the coordinated UL-DL interference mitigation approach may be as follows. First, the eNB macro can send its TDD UL/DL configuration to each eNB peak within its coverage via X2 or any other suitable interface. Each pico eNB can then implement Table 1 in its memory and can estimate the path loss to the macro eNB by listening to a reference signal from the macro eNB. If Path Loss is greater than a threshold plus a certain margin, a peak eNB can select the TDD UL/DL configuration according to its own traffic variation in UL and DL. Otherwise, the pico eNB may select a TDD UL/DL configuration with fewer conflicting subframes than the optimal configuration based on its own traffic variation, based on the cell TDD UL/DL configuration according to Table 1 .

In certain embodiments, signaling via X2 or SI may be explicitly specified for a macrocell to collect path loss information between associated picocells, for a cell to instruct the picocell for TDD UL/DL configuration, or for a picocell propose a TDD UL/DL configuration change for the cell decision.

Figure 3 illustrates a procedure according to certain embodiments. The procedure of Figure 3 can be performed, for example, by an eNode B of a macrocell. As shown in Figure 3, the method may include, at 310, determining the potential interference of a smaller cell in a network by including the smaller cell and a larger cell. The smallest cell and the largest cell here are simply two examples of different cells that can exist in a network such as a heterogeneous network. Thus, a smaller cell can be an example of a first cell and a larger callout can be an example of a second cell. Determination of potential interference may include determination of path loss. Determining potential interference may include determining whether an intercell interference between two smaller cells exceeds a threshold for at least one of the cells. The method may also include, at 315, determining a location of each associated smaller cell within a coverage of a larger cell, wherein the determination of potential interference is based on location. In addition, the method may include, at 317, maintaining a table of smaller interfering cells, where determining potential interference is based on the table. The table can be maintained, for example, by calculating the path loss based on the location determined in 315.

The method includes, at 320, controlling whether the smaller cell autonomously selects a time division duplex uplink-downlink configuration, based on the determined potential interference. The control may be based on determining that no other smaller cell is recorded in a portion of a table corresponding to the smaller cell. The control may include returning the smallest cell to at least one of a predetermined time division duplex uplink-downlink configuration or a balanced time division duplex downlink configuration based on a determined intercell interference state of the cell. net.

The method further includes, at 330, sending an authority indicator to a base station of the smaller cell when it is determined that the smaller cell should automatically select the configuration. It is not necessary for the smallest cell to have only one base station, or for the base station to have only one smallest cell. Sending the authority indication may include sending the authority indication through at least one of an interface X2 or an interface S1. When sending a negative authority indication, sending the authority indicator may be accompanied by sending the configuration to the smaller cell.

The method may further include, at 335, selecting the setting for the smallest cell, when it is determined that the smallest cell should not automatically select the setting. The selection may be based on the traffic load information of the smallest cell. Furthermore, the selection may be based on a pattern expected from the smallest cell, received from the smallest cell. The selection may include selecting a time division duplex configuration with fewer conflicting subframes with an interfered with cell than a configuration that more closely matches a smaller cell's uplink-download load.

Figure 4 illustrates another procedure according to certain embodiments. The procedure of Figure 4 can be performed, for example, by a picocell access point. As shown in Figure 4, the method includes, at 410, determining based on information from a base station of a larger cell, whether a smaller cell should control a split duplex uplink-downlink configuration. weather. The method also includes, at 420, applying a selected time division duplex uplink-downlink configuration based on the information.

The method also includes, at 430, providing traffic loading information to the base station when the smaller cell should not control the configuration. The traffic load information may include at least a ratio of instantaneous traffic between the downlink and uplink, an amount of data available pending scheduling on the downlink and uplink, or a ratio of traffic during a predefined statistical time scale. This traffic loading information may be sent periodically or on a trigger basis.

Figure 5 illustrates further procedure according to certain embodiments not covered by the claims. The procedure of Figure 5 can be performed, for example, by an eNode B of a picocell. As shown in Figure 5, a method may include, at 510, receiving a time division duplex uplink-downlink configuration from a second cell into a first cell. The method may also include, at 520, determining whether a time division duplex uplink-downlink configuration of the first cell should be optimized for an expected load or interference avoidance, based on potential interference with the second cell.

Figure 6 illustrates a system in accordance with certain embodiments of the invention. In one embodiment, a system may include two devices, such as the macro eNB 610 and the pico eNB 620. Each of these devices may include at least one processor, indicated respectively as 614 and 624. At least one processor is provided. memory on each device, and is indicated as 615 and 625, respectively. The memory may include computer program instructions or computer code contained therein. Transceivers 616 and 626 are provided, and each device may also include an antenna, illustrated respectively as 617 and 627. Other configurations of these devices may be provided, for example. For example, the macro eNB 610 and pico eNB 620 can be configured for wired communication, rather than wireless communication, and in such a case, antennas 617 and 627 would illustrate any form of communication hardware, without the need for an antenna. conventional.

Transceivers 616 and 626 may be independently a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that is configured for both transmission and reception.

The processors 614 and 624 may be incorporated by any computing or data processing device, such as a central processing unit (CPU), an application specific integrated circuit (ASIC), or a comparable device. The processors may be implemented as a single controller, or as a plurality of controllers or processors.

Memories 615 and 625 may independently be any suitable storage device, such as a non-transient computer readable medium. A hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory may be used. The memories can be combined into a single integrated circuit such as the processor, or they can be separated from it. Furthermore, the computer program instructions stored in memory and processable by the processors may be any suitable form of computer program code, eg, a compiled or interpreted computer program written in any suitable programming language.

Memory and computer program instructions can be configured, with the processor for the particular device, to cause a hardware appliance, such as the macro eNB 610 and pico eNB 620, to perform any of the procedures described above (see for example example, Figures 3-5). Thus, in certain embodiments, a non-transient computer-readable medium may be encoded with computer instructions that, when executed in hardware, perform a procedure such as one of the procedures described herein. Alternatively, certain embodiments of the invention may be implemented entirely in hardware.

Furthermore, although Figure 6 illustrates a system including a macro eNB and a peak eNB, embodiments of the invention may be applied to other configurations, and configurations involving additional elements, as illustrated herein. For example, other types of heterogeneous networks and network elements may be used.

One skilled in the art will readily understand that the invention as discussed above may be practiced with steps in a different order and/or with hardware elements in configurations that are different from those disclosed. Therefore, although the invention has been described based on these preferred embodiments, it will be apparent to those skilled in the art that certain modifications, variations and alternative constructions would be apparent, while remaining within the scope of the invention. In order to determine the measures and limits of the invention, therefore, reference should be made to the appended claims.

Claims (12)

Claim 1. A method for a communication network including a first cell and a second cell, the method comprising: receiving, by a base station in the first cell, an authority indicator from a base station in the second cell regarding a determination of whether the first cell should autonomously select a time division duplex uplink-downlink configuration; determining (410), by the base station of the first cell, based on the authority indicator, whether the first cell should autonomously select the time division duplex uplink-downlink configuration; applying (420), by the base station of the first cell, the autonomously selected time division duplex uplink-downlink configuration, when the first cell should autonomously select the time division duplex uplink-downlink configuration; Y providing (430), by the base station of the first cell, traffic loading information to the base station of the second cell when the first cell should not autonomously select the time division duplex uplink downlink configuration. 2. The method of claim 1, wherein the traffic load information comprises at least one of an instant traffic ratio between the downlink and the uplink, an amount of data available pending scheduling on the downlink and uplink, or a ratio of traffic over a predefined statistical time scale. The method of claim 1, wherein providing, by the base station of the first cell, the traffic loading information comprises sending the traffic loading information periodically or on a trigger basis. 4. A method for a communications network including a first cell and a second cell, the method comprising: determining (320), by a base station in the second cell, whether the first cell should autonomously select a time division duplex uplink-downlink configuration; sending (330), by the base station of the second cell, an authority indicator to a base station of the first cell regarding determining whether the first cell should autonomously select the split duplex uplink-downlink configuration of time; Y receiving, by the base station of the second cell, traffic load information from the base station of the first cell when the first cell should not autonomously select the time division duplex uplink-downlink configuration. 5. A first cell base station for a communications network including the first cell and a second cell, the first cell base station comprising: receiving means for receiving an authority indicator from a base station of the second cell with respect to determining whether the first cell should autonomously select a time division duplex uplink downlink configuration; determining means for determining, based on the authority flag, whether the first cell should autonomously select the time division duplex uplink-downlink configuration; applying means for applying the autonomously selected time division duplex uplink-downlink configuration, when the first cell must autonomously select the time division duplex uplink-downlink configuration; Y providing means for providing traffic load information to the base station of the second cell when the first cell should not autonomously select the time division duplex uplink-downlink configuration. 6. The base station of the first cell of claim 5, wherein the traffic load information comprises at least one of an instantaneous traffic ratio between the downlink and the uplink, an amount of available data waiting of the schedule on the downlink and uplink, or a ratio of traffic over a predefined statistical time scale. The base station of the first cell of claim 5, wherein providing the traffic loading information comprises sending the traffic information periodically or on a trigger basis. A second cell base station for a communications network including a first cell and a second cell, apparatus comprising: determining means for determining whether the first cell should autonomously select a time division duplex downlink uplink configuration; sending means for sending an authority indicator to a base station of the first cell regarding determining whether the first cell should autonomously select the time division duplex uplink downlink configuration; Y receiving means for receiving traffic load information from the base station of the first cell when the first cell should not autonomously select the time division duplex uplink-downlink configuration. 9. A non-transient computer-readable medium encoded with instructions that, when executed in hardware, enable a base station in a first cell to perform a procedure, the procedure comprising: receiving, by a base station in the first cell, an authority indicator from a base station in the second cell regarding a determination of whether the first cell should autonomously select a time division duplex uplink-downlink configuration; determining, by the base station of the first cell, based on the authority indicator, whether the first cell should autonomously select the time division duplex uplink-downlink configuration; applying, by the base station of the first cell, the autonomously selected time division duplex uplink-downlink configuration, when the first cell should autonomously select the time division duplex uplink-downlink configuration; Y providing, by the base station of the first cell, traffic loading information to the base station of the second cell when the first cell should not autonomously select the time division duplex uplink downlink configuration. 10. The non-transient computer-readable medium of claim 9, wherein the traffic load information comprises at least one of an instantaneous traffic ratio between the downlink and the uplink, an amount of available data waiting of the schedule on the downlink and uplink, or a ratio of traffic over a predefined statistical time scale. 11. The non-transient computer readable medium of claim 9, wherein providing, by the base station of the first cell, the traffic information comprises sending the traffic loading information periodically or on a trigger basis. 12. A non-transient computer-readable medium encoded with instructions that, when executed in hardware, perform a procedure, the procedure comprising: determining, by a base station in the second cell, whether the first cell should autonomously select a time division duplex uplink-downlink configuration; sending, by the base station of the second cell, an authority indicator to a base station of the first cell regarding determining whether the first cell should autonomously select the time division duplex uplink-downlink configuration; Y receiving, by the base station of the second cell, traffic load information from the base station of the first cell when the first cell should not autonomously select the time division duplex uplink-downlink configuration.